These are not halcyon days for the private equity industry. Returns are down. Fund-raising is trying. A tax increase looms.

Such challenges, however, did not deter one of the industry's titans, David Bonderman, from holding a 70th birthday party for himself and about 700 of his closest friends at the Wynn resort in Las Vegas Saturday night.

Paul McCartney was the surprise musical guest, playing for more than two hours. A newly minted septuagenarian himself, Mr. McCartney, the former Beatle, headlined a concert that also featured the comedian Robin Williams and the rocker John Fogerty. Mr. McCartney played several Beatles hits, including "Revolution" and, in a song befitting a 70th birthday, "The Long and Winding Road."

"We rocked the Wynn," wrote Charlotte Moss, a New York interior designer who attended the party, on her Twitter feed after the show.

The party for Mr. Bonderman, a founding partner of TPG, is the latest extravagant birthday celebration thrown by a private equity billionaire. During the summer of 2010, Leon D. Black of Apollo Global Management observed his 60th with a show by Elton John at his oceanfront estate in Southampton, on Long Island. Stephen A. Schwarzman's 60th, thrown at the Park Avenue Armory in 2007, featured a Rod Stewart concert and became a symbol of the new Gilded Age.

It was Mr. Bonderman, known to friends and colleagues as Bondo, who set the standard for these blowouts a decade ago. For his 60th birthday party at the Hard Rock Hotel and Casino in Las Vegas, he hired the Rolling Stones and John Mellencamp to perform.

Mr. McCartney and the other aging rockers who play these affairs are part of a growing cottage industry of stars that play private concerts for hire. Mr. Bonderman was not even the first moneyman to score Mr. McCartney as a headline act. In 2003, the investor Ralph V. Whitworth hired him to play at his wife's 50th birthday.

It is unclear how much Mr. McCartney earned for his performance, but music industry executives say that his asking price is well north of $1 million.

Even Mr. Fogerty, the former frontman for the rock band Creedence Clearwater Revival, reveled in sharing billing with Mr. McCartney. On his Facebook page, Mr. Fogerty, who played hit songs like "Proud Mary" and "Bad Moon Rising," posted a photo of himself and Sir Paul at Mr. Bonderman's fete.

Whatever Mr. McCartney's appearance fee, it was a rounding error for Mr. Bonderman, who is worth about $2.6 billion, according to Forbes magazine. A Harvard Law School graduate, he began his career as a lawyer in Washington before moving to Texas to work for the billionaire financier Robert Bass.

In 1993, he and his colleague, James Coulter, left Bass to start TPG. The firm has become one of the world's largest private equity firms, with stakes in businesses including the clothing company J. Crew and the Spanish-language broadcaster Univision.

Another large TPG holding, Caesars Entertainment, is the world's largest gambling company. That raises a question: Why didn't Mr. Bonderman throw his party at Caesars Palace or Harrah's, another Caesars-owned brand? Owen Blicksilver, a TPG spokesman, would not comment.

TPG has posted tepid returns in its most recent fund in part because two of its largest investments have soured. In 2008, the firm's $1.35 billion rescue financing of Washington Mutual was wiped out after the government seized the Seattle savings and loan. And TPG has written down nearly the entire value of its stake in Energy Future Holdings, the Texas utility acquired in the largest leveraged buyout ever.

TPG's issues, along with those of the broader private equity industry, were put aside last weekend. Party guests included Hamilton E. James, the president of the private equity firm Blackstone Group; Michael D. Eisner, the former chief executive of Walt Disney, and Marc E. Kasowitz, the New York trial lawyer. Mr. Bonderman donated $1,000 to a charity of each guest's choice.

Other than Ms. Moss's Twitter post, guests were unwilling to speak on the record or be quoted about the party. One said that was because he wanted to be invited to Mr. Bonderman's 80th. "Bruce Springsteen will only be 72 by then," he said.